Receiving Christmas cards from patients is the highlight of the year for Dr. Robert Montgomery. It shows he's in the right business: the business of caring for people.

Dr. Montgomery's most recent batch of cards came from kidney recipients who participated in a five-way domino, a transplant involving five donors and their recipients.

"We had four recipients who brought donors to the table who were incompatible. One was a mother/daughter pair and the others were all spouses. Then we had a woman come forward who wanted to give her kidney to anyone, and she was the altruistic donor."

With that scenario, Dr. Montgomery and his team at Johns Hopkins Hospital were able to match the donors with the appropriate recipients.

"You end up with an extra kidney at the end from the last pair," says Dr. Montgomery, "and so we gave that kidney to a woman who was at the top of the UNOS list; she put the most time in waiting. So she got a kidney without having a donor."

"UNOS" stands for United Network of Organ Sharing, the organization that coordinates organ transplants across the country.

In the case of Alex Pratt and the other kidney recipients in the show, they were involved in a three-way domino.

"We did our first three-way last year, but we did our first paired kidney exchange in 2001 ... So they were the second three-way paired kidney exchange," says Dr. Montgomery.

Dr. Montgomery would like to make the procedure available to all recipients in need of an organ. But creating a national program has ethical, logistical and legal issues currently being debated by the medical establishment. Dr. Montgomery says he understands why some might want to see the regional organ exchange program remain intact.

"For small [kidney transplant] programs it would seem to be a daunting task to get involved in this. And I think there is some concern about patients' families being split up and donors having to travel, but we are smart enough to get around those things."

Dr. Montgomery began his medical career at the University of Rochester, then he went on to Oxford, England, to receive his Ph.D. He has been at Hopkins for 20 years.

He took an interest in medicine while an undergraduate on a public health project in Africa. There he met traditional healers who practiced more than just medicine.

"It's not so much what they did as how they did it. Just the time they took with their patients. The way they connected with them, the eye contact. They genuinely cared about people."

Despite the obstacles, Dr. Montgomery is hopeful that a national kidney exchange program will become a reality so that everyone, no matter where they are located, has a chance at life. That, he says, is what his practice is all about.